How I "fake" a cloth diaper, plus doubling:
Ingredients: at least 1 disposable, at least 1 cloth diaper, a bit bigger than the average tea towel
Tools: none at all
Wear the disposable as normal. Hold the cloth longways down; tuck 1-2" into the waist at the front, without pulling off the top tapes. (Pull the ends of the cloth widthways to prevent bunching.) Reach behind and grab the cloth hanging down between the legs;pull up so the crotch is snug and tuck the end into the waist at the back, pulling widthways from both sides, again, to prevent bunching. There will be excess around the legs that gets tucked into the disp's leg holes. The net result is a pinless, velcroless cloth diaper.
When a disp is full, it usually leaks at the legs; the cloth wicks very well, sucking up fluid and soaking along its whole volume; sap (super absorbant polymer, the stuff inside disps) wicks poorly: when some absorbs fluid it turns into a gel that more water can't get through. That's why your disp can leak though parts are dry. So the cloth layer allows for better flooding without leaks